Many vehicles today are equipped with receiver-type trailer hitches. These types of trailer hitches typically are a square tube, normally 1¼″ or 2″ internal height and width, attached to the undercarriage of the vehicle. A second tube acts as a shank and includes outer dimensions slightly smaller than the internal dimensions of the receiver tube and is slidable within the receiver tube. The shank member is connected to the receiver tube by a pin inserted through the two tubes and locked or clipped to prevent relative movement between the two tubes.
Moreover, conventional techniques for locking threaded connections involve either mechanical metal split rings, external/internal tooth or Schnoor type metal spring metal-to-metal designs that gouge into the substrate causing surface deformities that can lead to accelerated rusting due to the penetration of the protective coating media by the locking device.
In highly corrosive environments like a receiver style hitch that encounters a variety of caustic substances, keeping the powder coating or paint on the hitch unmarred is critical when attaching, securing and removing towing products and accessories using methods that eliminate or remove dangerous and unwanted movement and noise in the hitch connection.
In another embodiment of the receiver-type trailer hitches, the shank is a solid, substantially square bar. Usually a 1¼″ or 2″ square with rounded corners. The solid shank is used more often with 1 or 1¼″ type hitch mounts.
The shank member may include a standard ball-mount for engaging with the hitch of a trailer or other wheeled vehicle. Another popular use for receiver hitches is the use as a coupling device for installing equipment racks, ski carriers, storage boxes and other types of carriers have been designed to use the above-described second tube to engage within a receiver hitch tube. This provides a universal system that allows a vehicle user to be able to use various trailer and carriers with a single coupling system.
A particular problem with the use of these receiver coupling systems is the clearance between the internal dimensions of the receiver tube and the external dimensions of the shank member. These tubes by necessity must have sufficient clearance to be able to be easily telescoped together. However, this clearance between the two tubes causes relative movement between the two tubes. The shank member tends to rattle or chatter within the receiver tube. This rattle or chatter is at best an annoyance and at worst can distract the driver or cause damage to the trailer or the carrier.
There have been a number of attempts to solve this problem in the past. These attempts all required the use of specially designed receivers, shanks, or accessories in order to reduce the rattle between the receiver and shank. Examples of these prior attempts are disclosed in U.S. Pat. No. 5,423,566; U.S. Pat. No. 5,593,172; U.S. Pat. No. 5,735,539; U.S. Pat. No. 5,879,102; U.S. Pat. No. 5,988,667; U.S. Pat. No. 6,010,049; U.S. Pat. No. 6,010,143; U.S. Pat. No. 6,010,144; and U.S. Pat. No. 6,105,989. These prior art devices either require specially designed receivers and shanks or use extraneous mounting devices to minimize the rattle between the receiver and the shank.
At present, there are a number of motion reducing designs for receiver style hitches useful for both hollow shanks and solid shanks. However, there persists a need for a device that will minimize the rattle between the receiver tube and the shank member.